At present, the mobile communication network technique have been developed to the Third Generation (referred to as 3G), and 3G networks are already deployed and commercially used in a large scale in the world. With the continuous popularization and promotion of data services and mobile Internet, international communication standards organizations are establishing the technology standards of Long Term Evolution (referred to as LTE) of the mobile communications, 4G and the like to meet the continuous development and promotion of network technologies and service capabilities. A Multiple Input and Multiple Output (referred to as MIMO) technology becomes one of the most critical core technologies in the LTE and future 4G technology as it is capable of improving a network service rate and link performance by adequately using an independent space propagation path.
At present, most of 2G and 3G networks utilize low-frequency-band resources, e.g., the Global System of Mobile Communication (referred to as GSM) is used in 900 MHz, the Code Division Multiple Access (referred to as CDMA) system is used in 800 MHz, and it is possible that the LTE and 4G will be used in the frequency bands of more than 2 GHz in the future, which means that the signal propagation performance of 2G and 3G networks is better than that of the LTE or 4G systems. Since it has been very difficult to increase the quantity of base stations at present, the network providers generally make a plurality of systems share one base station when deploying the LTE or 4G networks. In such a condition, if it will be sought that the base stations of LTE or 4G systems have the same coverage capability as that of the 2G/3G systems, MIMO multi-antenna technology must be utilized. Therefore, in order to improve the coverage capability of the LTE or 4G systems, it is necessary to increase the quantities of the MIMO antennas of the LTE and 4G systems as much as possible.
In the MIMO multi-antenna technology, a plurality of antennas is needed for signal transmission and reception. In an existing MIMO multi-antenna deployment scheme, a certain horizontal distance is generally spaced among the plurality of antennas so as to achieve multi-antenna signal transmission and reception. However, such a scheme will cause great difficulty for the network deployment of the network providers.
Specifically, for the MIMO antennas, general antenna configuration schemes contain 2×2, 4×2, 4×4 configurations and the like, which means that one base station needs to be configured with 4 antennas for signal transmitting and receiving. But now, in the 2×2 MIMO antenna scheme being a mainstream design, a dual-polarized antenna is generally used, so that the design requirements of the 2×2 MIMO antenna can be met because the dual-polarized antenna has weak correlation in the two polarization directions. The increasing of quantity of antennas makes the combination or diversity processing to signals of antennas be possible, which can improve the system performance greatly. However, for a 4×2 or a 4×4 MIMO antenna, further two antennas are needed besides of above dual-polarized antenna. It is conventional that the two independent dual-polarized antennas are horizontally spaced out a certain distance of 1-10λ (λ is a wavelength of a centre frequency point of a frequency band of the antenna). Although the specific value of the wavelength is related to the wireless propagation environment between a transmitter and a receiver, the distance is set to the larger the better so as to ensure weak correlation. Such a spacing mode in horizontal direction results in that an enough big space of the top surface of the base station is necessary for erecting two sets of antenna installation systems. Meanwhile, during the erecting of antenna installation system, it is necessary to ensure the downward inclination angles of the two horizontally-spaced dual-polarized antennas to be coincident and the quantity of antennas on the top surface of the base station is increased actually due to the horizontally-spaced MIMO antennas, which will increase the difficulty for the network providers to negotiate with the owner of the property for establishing the base station. Therefore, the utilizing of above MIMO antennas with horizontally-spaced mode is difficult in actual network construction and deployment to some extent.
The high attention of people to electromagnetic radiation problem results in that the quantity of independent physical antennas is hard to be increased in the site locations of many base stations and it is difficult for many base stations to have enough space to ensure the horizontally-spaced distance of a plurality of antennas, particularly when it is required to install 4 and more MIMO antennas. Therefore, the scheme adopting a plurality of physical antennas is not conducive to the deployment of the LTE and 4G networks.